Controlled Airspace
Definition
A generic term that covers the different classification of airspace (Class A, Class B, Class C, Class D, and Class E) and defined dimensions within which air traffic control service is provided to IFR flight and to VFR flights in accordance with the airspace classification.
In controlled airspace, it is the pilot's responsibility to ensure all requirements for communication and ATC radar advisories are met.
Traffic Advisories
If the controller's workload permits, traffic advisories will be provided to ALL aircraft.
Safety Alerts
Safety alerts are mandatory and provided to ALL aircraft. There are two types of safety alerts:
1. Terrain/Obstruction Alert – in the controller's judgment, an aircraft's altitude places it in an unsafe proximity to terrain and/or
obstructions.
2. Aircraft Conflict/Mode C Intruder Alert – if the controller observes another aircraft which places it in an unsafe proximity. When
feasible, the controller will offer the pilot an alternative course of action.
Class A Airspace
Definition
Generally, that airspace from 18,000 feet MSL up to and including FL600, including the airspace overlying the waters within 12 nautical miles of the coast of the 48 contiguous States and Alaska; and designated international airspace beyond 12 nautical miles of the coast of the 48 contiguous States and Alaska within areas of domestic radio navigational signal or ATC radar coverage, and within which domestic procedures are applied.
Operating Rules/Equipment Required
Must operate IFR unless otherwise authorized.
Charts: Class A is not specifically charted.
Class B Airspace
Definition
Generally, that airspace from the surface to 10,000 feet MSL surrounding the nation's busiest airports in terms of IFR operations or passenger enplanements. Class B airspace is individually taylor but normally consists of two or more layers (resembling an upside down wedding cake).
Operating Rules/Equipment Required
- ATC clearance is required prior to operating within Class B airspace
- Departing aircraft require a clearance to depart Class B airspace
- Aircraft must be equipped with an operable two-way radio capable of communicating with ATC on appropriate frequencies
- PIC must hold at least a private pilot certificate or student pilot seeking private pilot certification and meeting CFR requirements.
- If landing to or from primary airport and operating large turbine aircraft, operate at or above designated floors while within lateral boundaries
- Aircraft must be equipped with operable radar beacon transponder with automatic altitude reporting (Mode C). This requirement may be waived if a special request is submitted to ATC at least one hour prior to proposed operation.
- Aircraft not landing or departing from primary airport may obtain a clearance to transit the airspace when traffic conditions permit.
Mode C Veil
The airspace within 30 nautical miles of an airport (generally airports within Class B airspace areas), from the surface up to 10,000 feet MSL. Unless otherwise authorized, aircraft operating within this airspace must be equipped with automatic pressure altitude reporting equipment having Mode C capability.
Charts
Class B airspace is designated on Sectional Charts as a solid blue line surrounding the airspace.
The Mode C Veil is designated as a solid magenta circle. These are both shown in the picture below.
Class B airspace is generally surrounded by a white box on the VFR sectional. If you look along the edge of the white box, you will see the letters TAC. These letters stand for Terminal Area Chart. The terminal area chart is another publication that is roughly the same size as the sectional chart but only includes the area within the white box. In other words, it blows up the Class B area. The TAC includes a lot of additional information regarding flyways and special routes to enter and exit the Class B airspace. It is expected that the pilot will be using the TAC when flying within Class B airspace.
Class C Airspace
Definition
Generally, that airspace from the surface to 4,000 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower, are serviced by a radar approach control, and that have a certain number of IFR operations or passenger enplanements.
Although the configuration of each Class C airspace areas is individually tailored, the airspace usually consists of a 5 NM radius core surface area that extends from the surface up to 4,000 feet above the airport elevation, and a 10 NM radius shelf area that extends no lower than 1200 feet up to 4,000 feet above the airport elevation.
Operating Rules and Equipment Requirements
- No specific pilot certification required
- Two-way radio
- Operable radar beacon transponder with automatic altitude reporting equipment
- Establish two-way radio communication with ATC prior to entering Class C airspace
It is important to note that if the controller does not respond to the initial radio call with the aircraft callsign, then two-way radio communication has not been established and the aircraft cannot enter the Class C airspace.
Aircraft Speed
No aircraft may be operated below 2,500 feet above the surface within 4 nautical miles of the primary airport of Class C airspace at an indicated airspeed of more than 200 knots.
Aircraft Separation
Separation is provided within the Class C airspace and the outer area after two-way radio communications and radar contact are established. VFR aircraft are separated by any of the following:
- Visual separation
- 500 feet vertical; except when operating beneath a heavy jet
- Target resolution
Class D Airspace
Definition
Generally, that airspace from the surface to 2,500 feet above the airport elevation (charted in MSL) surrounding those airports that have an operational control tower. The configuration of each Class D airspace area is individually tailored and when instrument procedures are published, the airspace will normally be designed to contain the procedures.
Operating Rules and Equipment Requirements
- Operable two-way radio
- Establish two-way radio communication prior to entering airspace
It is important to note that if the ATC controller does not respond to the initial radio call with the aircraft callsign, then two-way radio communication has not been established.
For airports with a control tower that does not operate 24 hours a day, the Class E surface area rules or a combination of Class E rules to 700 feet above ground level and Class G rules to the surface will become applicable when the tower is closed. To find out the specifics for your Class D airspace, refer to the A/FD (airport facility directory).
Aircraft Speed
Aircraft operating at or below 2,500 feet above the surface within 4 nautical miles of the primary airport of Class D airspace must operate at an airspeed of 200 knots or less.
Charts
Class D airspace is charted on the Sectional with a segmented blue line.
Aircraft Separation
No separation services are provided to VFR aircraft.
Class E Airspace
Definition
Generally, if the airspace is not Class A, Class B, Class C, or Class D, and it is controlled airspace, it is Class E airspace.
Operating Rules and Equipment Requirements
There are no specific certificates, equipment or entry requirements for Class E airspace.
Charts
Class E airspace below 14,500 feet MSL is charted on the Sectional as either a segmented magenta line or a magenta vignette.
Vertical Limits
Except for 18,000 feet MSL, Class E airspace has no defined vertical limit but rather extends upward from either the surface or a designated altitude to the overlying or adjacent controlled airspace.
Types of Class E Airspace
- Surface area designated for an airport – When designated as a surface area for an airport, the airspace will be configured to contain all instrument procedures.
- Extension to a surface area – This airspace provides controlled airspace to contain standard instrument approach procedures without imposing a communication requirement for VFR pilots. These are normally extensions of Class B, C, and D airspace.
- Airspace used for transition – These are Class E airspace areas beginning at either 700 or 1,200 feet AGL used to transition to or from the terminal or en route environment.
- En Route Domestic Areas – Extend upward from a specific altitude and are en route domestic airspace areas that provide controlled airspace in those areas where there is a requirement t provide IFR en route ATC services but the Federal airway system is inadequate.
- Federal Airways – Federal Airways are Class E areas and, unless otherwise specified, extend upward from 1,200 feet to, but not including, 18,000 feet MSL. The colored airways are green, red, amber, and blue. The VOR airways are classified as Domestic, Alaskan, and Hawaiian.
- Offshore Airspace Areas – Extend upward from a specified altitude to, but not including, 18,000 feet MSL. These areas provide controlled airspace beyond 12 miles from the coast of the U.S. in those areas where there is a requirement to provide IFR en route ATC services and within which the U.S. is applying domestic procedures.
- Unless designated at lower altitudes, Class E airspace begins at 14,500 MSL to, but not including, 18,000 MSL overlying the 12 miles from the coast of the 48 contiguous States; the District of Columbia; Alaska, including the waters within 12 miles from the coast of Alaska, and that airspace above FL600; excluding the Alaska peninsula west of long. 150 00 00W and the airspace below 1,500 feet above the surface of the earth unless specifically so designated
Airspace Separation
No separation services are provided to VFR aircraft.
Class E Airspace floor begins at 700'
Class E Airspace begins at the ground (segmented magenta)
Class G Airspace (Uncontrolled Airspace)
Definition
Class G airspace (uncontrolled) is that portion of airspace that has not been designated as Class A, Class B, Class C, Class D, or Class E airspace.
VFR Requirements
Rules governing VFR flight have been adopted to assist the pilot in meeting the responsibility to see and avoid other aircraft. Minimum flight visibility and distance from clouds required for VFR flight are listed in Table 5-1 of AR 95-1 for Army Aviators.
